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The DABS Calibration Performance Monitoring Equipment Lincoln Laboratory Project Report
Project Report
ATC-89
The DABS Calibration Performance
Monitoring Equipment
J. C. Anderson
23 March 1979
Lincoln Laboratory
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
LEXINGTON, MASSACHUSETTS
Prepared for the Federal Aviation Administration,
Washington, D.C. 20591
This document is available to the public through
the National Technical Information Service,
Springfield, VA 22161
This document is disseminated under the sponsorship of the Department
of Transportation in the interest of information exchange. The United
States Government assumes no liability for its contents or use thereof.
T e c h n i c a l R e p o r t Doculllentation Page
1.
2.
Report No.
3. R e c i p i e n t ' s C a t a l o g N o .
Government Accession N o .
FAA-RD-78-151
-
5. Report D a t e
4. T i t l e and Subtitle
23 March 1979
The DABS Calibration Performance Monitoring Equipment
7.
6. Performing Organization Code
8.
Author(s)
Performing Organization Report N O .
ATC-89
J. C. Anderson
9.
Performing Organization Name and Address
Massachusetts Institute of Technology
Lincoln Laboratory
P.O. Box 73
Lexington, MA 02173
10.
Work U n i t N o .
11.
Contract or Grant N O .
Proj. No. 052-241-04
DC r-FA72-WAI-261
13.
12.
Department of Transportation
Federal Aviation Administration
Systems Research and Development Service
Washington, DC 20591
IS.
T y p e o f Report and P e r i o d Covered
Sponsoring Agency Name and Address
Project Report
14.
Sponsoring Agency Code
Supplementary N o t e s
The work reported in this document was performed a t Lincoln Laboratory, a center for research operated
by Massachusetts Institute of Technology under Air Force Contract F19628-78-C-0002.
16.
Abstract
The Discrete Address Beacon System (DABS) Calibration Performance Monitor Equipment
(CPME) is a special DABS transponder designed for installation a t a fixed site visible to one or
more DABS beacon sensors. The CPME is required for DABS sensor monopulse accuracy tests
and for calibration of the sensor off-boresite azimuth look-up table. In addition, the CPME
provides tests for DABS l h k integrity, by storing an uplink message and parroting i t back upon
command from the sensor.
This document contains all information necessary to obtain a general understanding of the
CPME system and its operation. Detailed information necessary for repair of the equipment is
not contained in this document, but is supplied with each CPME system.
17.
18.
K e y Wards
Discrete Address Beacon System
Calibration
System description
Beacon transponder
Monopulse accuracy
Link integrity
19. Security C l a s s i f . ( o f t h i s report)
F 1700.7
Document is available to the public through
the National Technical Information Service,
Springfield, VA 22151.
Security C l a s s i f . (of t h i s page)
Unclassified
Uncla ssFfied
Form DOT
20.
D i s t r i b u t i .n Statement
(8 - 7 2 )
Reproduct i o n o f completed pagc n u t l l o r i zed
21.
No. of P a g e s
56
CONTENTS
1.0
INTRODUCTION
1.1 G e n e r a l
1 . 2 O v e r v i e w o f CPME O p e r a t i o n
1.2.1
1.2.2
1.2.3
1.3
1.4
2.0
Reception
Transmission
Transponder I n t e r f a c e s
Diagnostic and Repair Features
Physical Features
FUNCTIONAL DESIGN
2.1
2.2
High-Power T r a n s m i t t e r
External Logic
2.2.1
2.2.2
2.2.3
ELRl C a r d
ELR2 C a r d
ELR3 C a r d
3.0
ENVIRONMENTAL SYSTEM
4.0
POWER DISTRIBUTION
4.1
4.2
4.3
Over-Voltage P r o t e c t i o n
Circuit Breakers
Power Consumption
APPENDIX A
CPME O p e r a t i n g P r o c e d u r e s
APPENDIX B
Exceptions and C l a r i f i c a t i o n s t o C a l i b r a t i o n and
P e r f o r m a n c e M o n i t o r E q u i p m e n t (CPME) E n g i n e e r i n g
R e q u i r e m e n t , FAA-ER-240-29
iii
LIST OF ILLUSTRATIONS
DABS C a l i b r a t i o n Performance Monitoring Equipment (CPME),
External View
DABS C a l i b r a t i o n Performance Monitoring Equipment (CPME),
System Block Diagram
CPME w i t h F r o n t Door Open
CPME, A s I n s t a l l e d
CPME Lockout Logic
T r a n s m i t t e r Duty Cycle L i m i t e r , Modulator Delay E q u a l i z e r
High Power T r a n s m i t t e r C o n t r o l Logic
Power-Up/Power-Fail
Circuitry
S e l e c t a b l e Turn-Around Delay C i r c u i t r y
Standard Message I n t e r f a c e P r o c e s s o r
Standard Message I n t e r f a c e P r o c e s s o r Flowchart
Environmental C o n t r o l s
Thermal O p e r a t i n g C h a r a c t e r i s t i c
1.0
INTRODUCTION
1.1 General
The DABS C a l i b r a t i o n and Performance Monitor Equipment (CPME) i s a
s p e c i a l purpose t e s t set r e q u i r e d t o v e r i f y DABS s e n s o r monopulse azimuth
a c c u r a c y , t o c a l i b r a t e t h e s e n s o r o f f - b o r e s i g h t azimuth look-up t a b l e * a t
a g i v e n s e n s o r s i t e , and f o r checking DABS d a t a l i n k i n t e g r i t y . CPMEs a r e
permanently i n s t a l l e d a t surveyed s i t e s w i t h i n t h e coverage p a t t e r n s of one
o r more DABS s e n s o r s , and each i s a s s i g n e d i t s own DABS d i s c r e t e a d d r e s s (wiredi n I D number). The weatherproof e n c l o s u r e , which p e r m i t s t h e CPME t o b e
o p e r a t e d u n a t t e n d e d o v e r a wide r a n g e of environmental c o n d i t i o n s , c o n t a i n s :
1)
A modified DABS t r a n s p o n d e r ,
2)
A phase-locked 1090 MHz o s c i l l a t o r ,
3)
A s p e c i a l h i g h d u t y c y c l e RF a m p l i f i e r f o r p r o v i d i n g
t h e h i g h l e v e l t e s t s i g n a l s needed a t t h e DABS s e n s o r , even
a t r a n g e s up t o 20 m i l e s ,
4)
S p e c i a l l o g i c t o p e r m i t t h e CPME t o send s t a t u s messages
and t o p a r r o t u p l i n k messages t o t h e s e n s o r ,
5)
S e l f - t e s t and d i a g n o s t i c c i r c u i t r y , and
6)
Power s u p p l i e s and c o n t r o l c i r c u i t s t o permit a l l of t h e
above t o o p e r a t e from AC power mains.
T h i s document d e s c r i b e s t h e CPME hardware and p r o v i d e s i n f o r m a t i o n n e c e s s a r y
t o understand i t s o p e r a t i o n . It does n o t p r o v i d e i n f o r m a t i o n s u f f i c i e n t l y
d e t a i l e d t o r e p a i r t h e CPME.
A d e t a i l e d o p e r a t i n g g u i d e i s provided a s Appendix A and c l a r i f i c a t i o n s
and e x c e p t i o n s t o t h e CPME s p e c i f i c a t i o n (FAA-ER-240-29 Amendment 1, Spec.
Change 1 ) a r e i n c l u d e d a s Appendix B .
Each CPME i s provided w i t h a weather p r o t e c t e d horn a n t e n n a i n t e n d e d
f o r i n s t a l l a t i o n a t o p a t a l l tower, 150 f e e t of antenna c a b l e , and a power
cable.
(See F i g u r e 1 )
.
1.2
Overview of CPME O p e r a t i o n
1.2.1
Reception
DABS i n t e r r o g a t i o n s i g n a l s ( s e e F i g u r e 2) p a s s through a c i r c u l a t o r , a
f i l t e r ( t o e l i m i n a t e out-of-band s i g n a l s ) , a power l i m i t e r ( f o r front-end
*A s
s p e c i f i e d i n FAA ER-240-26,
S e c t i o n 3 . 4 . 1 1 and 4 . 5 . 4 . 3 .
CONVENIENCE
OUTLET
SUN SHIELD
I
AIR-TO-AIR ,
HEAT
E ~ A N G E R ~ 1
-
INDICATOR^:---/<
LIGHTS
,
POWER AND
ANTENNA
CABLES
I
I
DABS CPME
UNIT
ADJUSTABL
AZIMUTH
ANTENNA
MOUNT
Fig. 1.
DABS Calibration Performance Monitoring Equipment (CPME), external view
p r o t e c t i o n ) , and a v a r i a b l e a t t e n u a t o r (used t o set t h e r e c e i v e r s e n s i t i v i t y )
b e f o r e r e a c h i n g t h e DABS t r a n s p o n d e r .
The DABS t r a n s p o n d e r r e c e i v e r i s employed,
b u t o n l y one channel i s used ( i . e . , t h e t r a n s p o n d e r ' s d i v e r s i t y c a p a b i l i t y i s
n o t u s e d ) . Mode decoding and r e p l y encoding a r e performed by u n a l t e r e d t r a n s ponder c i r c u i t r y .
The TTL r e p l y l e a v e s t h e t r a n s p o n d e r and i s d e l a y e d f o r 0 , 128, o r 256
microseconds a s d e s i r e d ( c a u s i n g t h e CPME t o a p p e a r a s though i t i s 0 , 1 0 ,
o r 20 m i l e s f u r t h e r away from t h e s e n s o r t h a n i t a c t u a l l y i s ) . A f t e r t h i s
a d d i t i o n a l turnaround d e l a y , t h e TTL s i g n a l n e c e s s a r y t o g e n e r a t e a r e p l y
i s s e n t t o .one of two m o d u l a t o r s : e i t h e r high-power o r low-power.
1.2.2
Transmission
The RF t r a n s m i t t e r s e c t i o n i s d r i v e n e i t h e r by a n u l t r a - s t a b l e 1090 MHz
o s c i l l a t o r , which i s i s o l a t o r p r o t e c t e d , o r by a n e x t e r n a l v a r i a b l e frequency
s i g n a l s o u r c e ( d u r i n g DABS s e n s o r a c c e p t a n c e t e s t i n g ) . The CW s i g n a l i s f e d
i n t o a v a r i a b l e a t t e n u a t o r . T h i s a t t e n u a t o r sets t h e RF r e p l y l e v e l i f t h e
CPME i s o p e r a t i n g i n t h e low-power mode, o r sets t h e d r i v e l e v e l t o t h e power
a m p l i f i e r i f t h e CPME i s o p e r a t i n g i n t h e high-power mode.
The t r a n s p o n d e r ' s t r a n s m i t t e r s e c t i o n i s n o t used, and t h e o r i g i n a l
power s u p p l y h a s been removed from t h e t r a n s p o n d e r . An a d d i t i o n a l f r o n t
p a n e l c o n n e c t o r h a s been added t o t h e t r a n s p o n d e r t o a l l o w e x t e r n a l power
i n p u t and t o communicate w i t h t h e e x t e r n a l l o g i c r a c k .
I n t h e low-power mode, t h e CW s i g n a l i s modulated by a PIN d i o d e s w i t c h
and t h e n f i l t e r e d t o e l i m i n a t e out-of-band s i g n a l s . The modulated s i g n a l
i s sampled by a b u i l t - i n power m o n i t o r i n g system c o n s i s t i n g of a d i r e c t i o n a l
c o u p l e r , p a d s , and a c a l i b r a t e d c r y s t a l d e t e c t o r . Output from t h e sampling
d e t e c t o r can b e viewed on a n o s c i l l o s c o p e , and t h e power o u t p u t of t h e CPME
can b e determined u s i n g c a l i b r a t i o n i n f o r m a t i o n provided w i t h e a c h CPME.
The power monitor system i s most u s e f u l when t h e CPME i s o p e r a t e d i n t h e
high-power mode, a s low-power s i g n a l s a r e t y p i c a l l y t o o s m a l l t o b e measured
a c c u r a t e l y . Modulated r e p l y s i g n a l s e x i t through t h e c i r c u l a t o r and a r e f e d
t o t h e antenna.
The maximum o u t p u t i n t h e low-power mode, +20 dBm a t t h e CPME
RF p o r t , a l l o w s t h e CPME t o b e p l a c e d up t o 2000 f e e t away from t h e s e n s o r .
The high-power mode a l l o w s t h e CPME t o b e p l a c e d up t o 20 m i l e s from t h e
s e n s o r , a s i t p r o v i d e s o u t p u t power a s h i g h a s +45 dBm a t t h e CPME RF p o r t .
The high-power mode i s n e c e s s a r y i n c a s e s where t h e CPME i s t o b e s h a r e d w i t h
more t h a n one s e n s o r ( i n t h i s c a s e more t h a n one d i r e c t i o n a l horn a n t e n n a
would b e f e d from one CPME).
O p e r a t i o n i n t h e high-power mode i s s i m i l a r t o t h a t i n t h e low-power mode,
e x c e p t t h a t a s e p a r a t e modulation, a m p l i f i c a t i o n , and a t t e n u a t i o n system i s
used. The CW s i g n a l from t h e low-power v a r i a b l e a t t e n u a t o r i s f u r t h e r a t t e n u a t e d ( t o p r o t e c t t h e a m p l i f i e r ' s RF i n p u t ) , and t h e n fed t o t h e RF power a m p l i f i e r .
Here, t h e CW i s b o t h modulated and a m p l i f i e d , and t h e r e p l y power l e v e l i s t h e n
set by a high-power v a r i a b l e a t t e n u a t o r .
The a m p l i f i e r u n i t i t s e l f i s a 4-stage t r i o d e t u b e a m p l i f i e r . Other
components of t h e high-power a m p l i f i e r system a r e : power s u p p l i e s (+6V, +28V,
and +1000V), s w i t c h e s f o r r e - r o u t i n g t h e RF when changing from low t o highpower mode ( s e e F i g . 3 ) , a high-power v a r i a b l e a t t e n u a t o r , and a modulator f o r
t h e tube amplifier.
I n t h e e v e n t t h a t any of t h e s e i t e m s should f a i l , t h e
CPME w i l l s t i l l f u n c t i o n c o r r e c t l y when switched t o t h e low-power mode.
1.2.3
Transponder I n t e r f a c e s
The t r a n s p o n d e r a l s o i n t e r f a c e s w i t h t h e e x t e r n a l l o g i c r a c k v i a t h e
Standard Message I n t e r f a c e (SMI). Data i n t e r c h a n g e between t h e t r a n s p o n d e r
and e x t e r n a l l o g i c r a c k v i a t h e SMI a l l o w s t h e CPME t o o p e r a t e i n a test mode
wherein t h e CPME " p a r r o t s " u p l i n k messages. The SMI d a t a c a p a b i l i t y a l s o
a l l o w s t h e CPME t o r e p o r t i t s s t a t u s t o t h e s e n s o r . Thus a "remote d i a g n o s t i c s "
function i s provided.
S t a t u s r e p o r t i n g p r o v i s i o n s a r e i n c l u d e d t o t r a n s m i t ( a s a Comm-B downlink
message): e n c l o s u r e over-and-under t e m p e r a t u r e , 1090-MHz o s c i l l a t o r out-ofphase-lock c o n d i t i o n , power f a i l u r e c o n d i t i o n , m i s c e l l a n e o u s hardware f a u l t s
and i n t e r r o g a t i o n l o c k o u t s t a t e s . The e n t i r e s t a t u s r e p o r t i n g system can b e
inhibited i f desired.
1.3
D i a g n o s t i c and R e p a i r F e a t u r e s
I n a d d i t i o n t o t h e d u a l t r a n s m i t t e r f e a t u r e and s t a t u s r e p o r t i n g t o
s e n s o r f e a t u r e s t h e CPME i n c l u d e s o t h e r b u i l t - i n test and d i a g n o s t i c a i d s .
E x t e n s i v e b u i l t - i n d i a g n o s t i c l o g i c c i r c u i t s e x i s t t o d e t e c t hardware f a i l u r e s
and t h e r e b y f a c i l i t a t e r e p a i r . The r e s u l t s of t h e s e b u i l t - i n test c i r c u i t s
a r e d i s p l a y e d on a main CPME c o n t r o l p a n e l , a l o n g w i t h v a r i o u s o t h e r i n d i c a t o r s
and c o n t r o l s f o r t h e system. Another b u i l t - i n d i a g n o s t i c t o o l i s a d i g i t a l
voltmeter.
T h i s f e a t u r e a l l o w s a repairman t o q u i c k l y check a l l seven of
t h e CPME's power s u p p l i e s by s e t t i n g a s i n g l e c o n t r o l .
F i n a l l y , t h e Bendix t r a n s p o n d e r i s equipped w i t h a test j a c k on i t s f r o n t
p a n e l . Various i n t e r n a l s i g n a l s a r e brought o u t t o t h i s c o n n e c t o r s o t h a t
t h e y c a n be viewed w i t h a n o s c i l l o s c o p e and f a u l t s i s o l a t e d .
RF POWER OUTPUT
MONITOR (TO
EXTERNAL
OSCILLOSCOPE 1
\
SUN SHIELD
Fig. 3.
ENVIRONMENTAL
SYSTEM CONTROLS
(TEMPERATURE
SWITCHES)
I
CPME w i t h f r o n t door open
6
CIRCUIT BREAKER
SWITCHES
1.4
Physical Features
The CPME u n i t f e a t u r e s a l o c k a b l e w e a t h e r - t i g h t e n c l o s u r e f o r outdoor
s t a n d - a l o n e o p e r a t i o n , a n a i r - t o - a i r h e a t exchanger f o r c o o l i n g , a 500 w a t t
h e a t e r , a s u n shade, mounting l e g s , h i g h l y v i s i b l e e x t e r n a l "power on" and
" f a u l t " i n d i c a t o r lamps, and a n e x t e r n a l e l e c t r i c a l convenience o u t l e t s o
t h a t o s c i l l o s c o p e s and o t h e r t e s t equipment can be powered a t t h e CPME i f
d e s i r e d . O v e r a l l dimensions of t h e CPME u n i t , e x c l u s i v e of s u n s h i e l d and
mounting l e g s , a r e 30" wide, 35" h i g h , and 16" deep. Legs r a i s e t h e e n c l o s u r e
12" above t h e mounting pad.
Its weight i s approximately 200 pounds.
F i g u r e 3 i l l u s t r a t e s t h e u n i t a s i t would b e s e e n by s e r v i c e p e r s o n n e l .
A f l u s h door (30" x 35") p e r m i t s a c c e s s t o a l l components. I n a d d i t i o n t o
t h e f r o n t d o o r , a s m a l l l o c k a b l e r e a r door a l l o w s e a s y a c c e s s t o t h e w i r e wrap backplane of t h e l o g i c r a c k .
The CPME antenna c o n s i s t s of an e n v i r o n m e n t a l l y p r o t e c t e d horn a n t e n n a ,
a coax-to-waveguide a d a p t e r , and a mount. The mount f e a t u r e s 360' azimuth
a d j u s t m e n t f o r "aiming" t h e a n t e n n a (no e l e v a t i o n a d j u s t m e n t i s n e c e s s a r y ) .
A t y p i c a l i n s t a l l a t i o n i s i l l u s t r a t e d i n F i g u r e 4.
RADOME
ADJUSTABLE AZ[MUTH
ANTENNA MOLINT
CALIBRATION AND PERFORMANCE
MONITORING EQUIP MENT
POWER
Fig. 4.
CPME, a s i n s t a l l e d
2.0
FUNCTIONAL DESIGN
2.1
High-power T r a n s m i t t e r
A high-power, h i g h d u t y c y c l e t r a n s m i t t e r was developed f o r t h e DABS
CPME t o s a t i s f y a requirement d i c t a t e d by ( 1 ) t h e p o s s i b i l i t y of s h a r i n g
one CPME between two o r more s e n s o r s and ( 2 ) t h e high-power l e v e l (-24 dBm)
r e q u i r e d a t t h e s e n s o r d u r i n g monopulse a c c u r a c y tests*. The h i g h d u t y c y c l e
requirement i s based on t h e Texas I n s t r u m e n t s DABS monopulse c a l i b r a t i o n and
accuracy t e s t a l g o r i t h m i n which 80 i n t e r r o g a t i o n s a r e t r a n s m i t t e d d u r i n g a
44 msec beam d w e l l t i m e i n t e r v a l (PRF = 1800 r e p l i e s p e r second r e q u i r e d from
CPME)
.
T e s t s on t h e high-power t r a n s m i t t e r have v e r i f i e d t h a t i t i s a b l e t o
s u p p o r t t h i s h i g h PRF r e q u i r e d d u r i n g monopulse c a l i b r a t i o n . The c a p a b i l i t y
of producing p u l s e r e p e t i t i o n f r e q u e n c i e s of 2000 r e p l i e s l s e c f o r DABS s h o r t
and 1000 r e p l i e s l s e c f o r DABS l o n g s i m u l a t e d r e p l i e s h a s a l s o been e s t a b l i s h e d .
Simulated DABS s h o r t r e p l i e s a r e 60 usec t r a n s m i s s i o n s of a 50% d u t y c y c l e
1 MHz s i g n a l . Simulated DABS long r e p l i e s a r e 116 u s e c t r a n s m i s s i o n s of a
50% d u t y c y c l e 1 MHz s i g n a l . Note t h a t t h e o v e r a l l d u t y c y c l e should n o t
exceed 0.005, when averaged o v e r a 1 second i n t e r v a l .
The RF power a m p l i f i e r t u b e used i s a General E l e c t r i c model C-2173
microwave t r i o d e a m p l i f i e r . The C-2173 i s a 4 s t a g e a m p l i f i e r o p e r a t i n g
a t 1090 MHz c e n t e r frequency c a p a b l e of p r o v i d i n g a n o u t p u t of a t l e a s t 300
w a t t s peak a t 0 . 0 1 d u t y , w i t h a n i n p u t of 1 0 m i l l i w a t t s .
The RF i n p u t i s a CW s i g n a l t o t h e f i r s t s t a g e w i t h t h e c a t h o d e s of t h e
f i r s t two s t a g e s modulated t o g e n e r a t e t h e r e q u i r e d RF p u l s e s . The l a s t two
s t a g e s a r e s e l f - b i a s e d u s i n g a 22 v o l t Zener on t h e c a t h o d e s and a r e RF keyed
by t h e p u l s e s of RF g e n e r a t e d by t h e f i r s t two s t a g e s .
The o u t p u t v s . i n p u t c h a r a c t e r i s t i c f o r t h e C-2173 shows t h a t t h e a m p l i f i e r
h a s c o n s i d e r a b l e compression. T h i s i s d e s i r a b l e f o r s t a b i l i t y w i t h i n p u t and
w i t h l i f e . However, i t may be p o s s i b l e t o o v e r d r i v e one of t h e i n t e r m e d i a t e
s t a g e s w i t h o u t o b t a i n i n g e x c e s s i v e o u t p u t power i f t h e i n p u t i s allowed t o go
beyond t h e 10 m i l l i w a t t l e v e l .
The power o u t p u t may
Normal power o u t p u t i s 400 w a t t s a t 1000 v o l t s B+.
I t i s n o t recommended t h a t t h e B+ l e v e l b e r a i s e d
v a r y c o n s i d e r a b l y w i t h B+.
over 1000 v o l t s .
2.2
E x t e r n a l Logic
Logic n o t c o n t a i n e d i n t h e t r a n s p o n d e r i s termed e x t e r n a l l o g i c . T h i s
l o g i c i s c o n t a i n e d on t h r e e wire-wrap b o a r d s , ELR1, ELR2 and ELR3, l o c a t e d i n
* See
FAA-ER-240-26,
p. 534, paragraph 4.5.4.3.1.
the External Logic Rack* (see Fig. 3).
ELRl contains the CPME lockout logic, the transmitter duty cycle
limiter, the modulator delay equalizer, the high-power transmitter control logic, and the power-up/power-fail circuitry.
ELR2 contains the logic necessary to delay CPME replies by 0, 128,
or 256 microseconds (in addition to those delays specified
for DABS and ATCRBS replies.)
ELR3 contains logic which allows the CPME to communicate with the
DABS sensor via the DABS data link.
When referring to logic signal names on the diagrams shown in the
following sections, note that the following nomenclature has been standardized:
Logic Signal Name
Inverter (amplifier) output
Flip-flop
Gate
Latch
Multiplexer
Open collector signal
Active low signal
NAME.A
NAME.F
NAME.G
NAME L
NAME .M
NAME*
NAME
.
2.2.1
Meaning
ELRl Card
2.2.1.1
CPME Lockout Logic
2.2.1.1.1 The ATCRBS lockout function in the Bendix
transponder is consistent with CPME requirements, and no modification was
necessary.
2.2.1.1.2 The ATCRBSIDABS All-Call, Auxiliary
(DABS-only) All-Call and Auxiliary Discrete Reply lockout system in the
transponder was replaced with the system shown in Figure 5. When an interrogation is received, it is held in the transponder's uplink register. If the
uplink is valid and is of a type which has not previously been locked out,
then three uplink bits (IT and the two DL bits) are taken together with the
present lockout states to address a PROM which will determine the next lockout
state. The next lockout state is determined as in paragraph 4.4.3.1 of FAARD-74-62 (ATC-30).
2.2.1.1.3 The standard timeout is initiated each
time the CPME replies to a discrete address interrogation from a standard DABS
sensor. When the standard timer times out, only the ATCRBSIDABS All-Call
lockout flip-flop is cleared.
>k
The External Logic Rack has three unused slots for future expansion. Available
power supplies (+5V, +12V and -12V) can provide ample additional current.
sn01
msCnElt I N l E I P m n l X M
10 VLLID huu YOT L#utD OUT
I
I
UPLIMY
NllSlFR
1
AL
AlCIBS LOCKOUl
-tk
8
Pi w l m w
rnO(tICD urn0
0
a
IICR~/BU
tw or IRU(CUISUOW
AXIUIE~K
W.CALL ~ o w o u l
IBXILIAU~ AU.CW~ r w m I
NEW L @ C ~ O U l
SICWLS 0
CDIIlPR I L
uscrn ltnr wan I
lUUlPOWKI
AlUUI/Wl A U t U
IlYUID
1lMkOUI
1st
~
D
IItYt
J
~
OIRLUIO.
I
Y Ill
fitnAai
e w t t t
w
E D
~
COUIU. IS C L U I r n
blEU DISCIK11 AWMlS
N I K U P M l l O l fMY
I I A M M D W U.YI UI n c c t m
AUXILILR*
TIY~DUT
1 Dl1
BINA~
counna
otu
I
TmnRX
1
I
IUIIUARY
tLNk
I
I
Fig. 5.
1
AUIILIIRi 1 l Y E l
I
I
0.
Y
.h
CPME lockout l o g i c
U I NE
O(rnlA1OI
1AC
ADJUST
2.2.1.1.4
The a u x i l i a r y timeout i s i n i t i a t e d each
t i m e t h e CPME r e p l i e s t o a d i s c r e t e a d d r e s s i n t e r r o g a t i o n from any DABS s e n s o r ,
e i t h e r s t a n d a r d o r a u x i l i a r y . When t h e a u x i l i a r y t i m e r t i m e s o u t , a l l f o u r
l o c k o u t f l i p - f l o p s a r e reset.
2.2.1.1.5
When a n ATCRBS~DABS A l l - C a l l i n t e r r o g a t i o n i s r e c e i v e d , t h e ATCRBS~DABS A l l - C a l l f l i p - f l o p i s s e t . I f t h e CPME
i s locked o u t t o ATCRBSIDABSA l l - C a l l s and n o t t o ATCRBS, t h e n the.ATCRBS/DABS
a l l - c a l l s i g n a l i s g a t e d t o z e r o , r e g a r d l e s s of whether t h e r e c e i v e d i n t e r r o g a t i o n i s a n ATCRBS~DABS a l l - c a l l o r n o t . When t h i s c o n d i t i o n o c c u r s , t h e CPME
r e p l i e s ~o.ATCRBS/DABS
a l l - c a l l s w i t h t h e p r o p e r t y p e of ATCRBS r e p l i e s ( e i t h e r
mode A o r mode C). T h i s a l l o w s t h e CPME t o "look l i k e " a n ATCRBS t r a n s p o n d e r
f o r purposes of t e s t i n g t h e s e n s o r w i t h ATCRBS r e p l i e s .
2.2.1.2
T r a n s m i t t e r Duty Cycle L i m i t e r
The CPME must be c a p a b l e of r e p l y i n g t o a l l combinations of ATCRBS and
DABS i n t e r r o g a t i o n s f o r which t h e r e s u l t i n g t r a n s m i t t e r d u t y c y c l e i s n o t
g r e a t e r t h a n 0.005, averaged over a 1-second p e r i o d . T h i s means t h a t t h e
t r a n s m i t t e r must b e a b l e t o p r o v i d e RF o u t p u t f o r a t o t a l of 5 m i l l i s e c o n d s
each second.
A s i m p l e numerical i n t e g r a t i o n scheme c a n be used t o d e t e r m i n e t h e overa l l d u t y c y c l e , a s i l l u s t r a t e d i n F i g . 6 . The TTL r e p l y , which h a s gone
through t h e s e l e c t a b l e 0 , 128, o r 256 psec d e l a y (DELAYED REPLY), i s used t o
e n a b l e a high-speed c o u n t e r . Every ATCRBS r e p l y p u l s e g a t e s t h e c o u n t e r on
l o n g enough t o i n c r e a s e t h e count by f o u r , and e a c h DABS p u l s e i n c r e a s e s t h e
count by e i t h e r f i v e o r t e n , depending upon t h e b i t p a t t e r n i n t h e r e p l y .
When t h e count r e a c h e s 50,176, c o r r e s p o n d i n g t o a minimum of 5 m i l l i s e c o n d s
of RF "on" t i m e , a f l i p - f l o p i s set which i n d i c a t e s t h a t a d u t y c y c l e f a u l t h a s
o c c u r r e d . T h i s s i g n a l i s d i s p l a y e d on t h e CPME c o c t r o l p a n e l , and a b i t i s
s e t i n f u r t h e r CPME r e p l i e s t o i n d i c a t e t h a t a f a u l t h a s o c c u r r e d . The CPME
c o n t i n u e s t o o p e r a t e normally u n t i l t h e c o u n t e r r e a c h e s 57,344, c o r r e s p o n d i n g
t o 5.7 m i l l i s e c o n d s of RF "on" t i m e . A t t h i s p o i n t a f l i p - f l o p i s set t o
i n d i c a t e t h a t t h e d u t y c y c l e h a s been exceeded, and f u r t h e r r e p l i e s a r e
i n h i b i t e d by g a t i n g them o f f . A t t h e end of e v e r y second, a p u l s e comes from
a p u l s e g e n e r a t o r t o c l e a r t h e f a u l t c o n d i t i o n s , i f a n y , and r e s e t t h e c o u n t e r .
Note t h a t t h e maximum d u t y c y c l e of t h e t u b e a m p l i f i e r i s 0.01, s o s a f e
operation i s assured.
2.2.1.3
Modulator Delay E q u a l i z e r
F i g u r e 6 shows a 120 n s e c d e l a y d i f f e r e n c e between r e p l i e s t o t h e PIN
. i o d e s w i t c h and t h e power a m p l i f i e r . T h i s d e l a y l i n e compensates f o r t h e
' a c t t h a t t h e PIN d i o d e s w i t c h h a s a v e r y f a s t turn-on c h a r a c t e r i s t i c , w h i l e
t h e t u b e a m p l i f i e r d o e s n o t . Thus t h e d e l a y between t h e TTL s i g n a l and RF
turn-on i s t h e same i n b o t h high- and low-power modes. T y p i c a l t o t a l d e l a y
between t h e TTL s i g n a l on t h e ELRl c a r d and t h e RF o u t p u t ( i n e i t h e r high- o r
low-power mode) i s 220 n s e c .
2.2.1.4
High-power T r a n s m i t t e r C o n t r o l Logic
When i n i t i a l l y t u r n i n g t h e high-power t r a n s m i t t e r o n , i t i s n e c e s s a r y t o
p r o v i d e s e v e r a l i n t e r l o c k s and d e t e c t i o n of f a u l t c o n d i t i o n s t o avoid damaging
t h e t u b e u n i t . The system i s i l l u s t r a t e d i n F i g . 7 . When power i s f i r s t t u r n e d
on o r when t h e CPME i s i n t h e INITIALIZE mode, a RESET s i g n a l i s g e n e r a t e d
which a l l o w s t h e s t a t e of t h e HIGH-POWER/LOW-POWER MODE s e l e c t s w i t c h t o be
l a t c h e d . The HIM0DE.L s i g n a l s t a t e i s d i s p l a y e d on t h e CPME f r o n t p a n e l
a s "HI-PWR XMTR SEL" f o r high-power mode s e l e c t e d . The p r e s e n c e of t h i s
s i g n a l does n o t i n d i c a t e t h a t t h e high-power t r a n s m i t t e r i s i n f a c t a c t i v e ;
i t merely i n d i c a t e s t h a t w e wish i t t o be a c t i v e . The HIM0DE.L s i g n a l i s
used t o s w i t c h i n t h e a p p r o p r i a t e elements f o r e i t h e r high-or low-power
o p e r a t i o n by c o n t r o l l i n g a DPDT (double p o l e , d o u b l e throw) s w i t c h . When
t h e DPDT s w i t c h ' s b u i l t - i n i n d i c a t o r c i r c u i t s show t h a t t h e s w i t c h i s i n t h e
high-power p o s i t i o n , t h e HIPWR s i g n a l goes t r u e . T h i s s i g n a l a c t i v a t e s t h e
power s u p p l i e s f o r t h e t u b e a m p l i f i e r , and g i v e s a v i s u a l i n d i c a t i o n ( t h e l K V ,
6V ACTIVE LED on t h e c o n t r o l p a n e l ) t h a t t h e high-power t r a n s m i t t e r s e c t i o n
i s ready.
2.2.1.5
Power-up/Power-fail
Circuitry
Refer t o F i g u r e 8 . When t h e CPME i s powered-up o r i n i t i a l i z e d , t h e POWERFAIL s i g n a l goes t r u e and t h e ENABXMIT ( e n a b l e t r a n s m i s s i o n ) goes f a l s e . A f t e r
64 s e c o n d s , t h e ENABXMIT s i g n a l goes t r u e , which a l l o w s t h e CPME t o r e p l y t o
interrogations.
The 64-second timeout i s t o a l l o w t h e t u b e a m p l i f i e r ample
time t o warm up, a s w e l l a s t o a l l o w v a r i o u s t r a n s p o n d e r and CPME t i m e r s t o
time o u t . When a n o t h e r 64 seconds have e l a p s e d ( i . e . , 128 s e c a f t e r t h e CPME
h a s been i n t h e RUN mode w i t h power on) t h e POWER-FAIL f l a g i s c l e a r e d , and
t h e CPME r u n s normally.
The POWER-FAIL f l a g , when a c t i v e , simply i n d i c a t e s
t h a t power t o t h e CPME h a s been o f f f o r a w h i l e o r t h a t t h e CPME h a s r e c e n t l y
been i n i t i a l i z e d .
T h i s f e a t u r e i s u s e f u l i n performing remote d i a g n o s t i c s
from t h e s e n s o r , a s i t v e r i f i e s t h a t a CPME f a i l u r e has o c c u r r e d r a t h e r t h a n
a s e n s o r f a i l u r e and a l s o i n d i c a t e s t h a t someone may have changed CPME c o n t r o l
s e t t i n g s . The POWER-FAIL f l a g i s s e n t i n r e p l y t r a n s m i s s i o n s , a s a f a u l t b i t ,
d u r i n g t h e f i r s t 64 seconds t h a t t h e CPME i s a b l e t o r e p l y ( i . e . , 64 t o 128
s e c a f t e r power-up o r i n i t i a l i z a t i o n ) .
2.2.2
ELR2 Card
F i g u r e 9 shows t h e l o g i c needed t o d e l a y CPME r e p l i e s by 0 , 128, o r 256
microseconds.
2.2.2.1
Delay S e l e c t i o n Logic
A s w i t c h on t h e CPME c o n t r o l p a n e l i s used t o s e l e c t t h e d e s i r e d t u r n around d e l a y . The s t a t e of t h i s s w i t c h i s l a t c h e d a f t e r power-up o r i n i t i a l i z a t i o n ,
and cannot be changed u n l e s s t h e CPME i s r e - i n i t i a l i z e d .
RESET
(SEL FIG.^)
1
FROM
1Ht
PULSE
2,
GENERATOR
(SEE FIG.^)
Fig. 8.
Power-up/power-fail circuitry
2.2.2.2
Zero Delay S e l e c t e d
If z e r o d e l a y i s d e s i r e d , t h e "D0" s i g n a l goes t r u e , which i n t u r n
g e n e r a t e s a s i g n a l "NODEL" (no d e l a y ) . The "NODEL" s i g n a l t r u e c o n d i t i o n
h o l d s a l l t h e d e l a y c i r c u i t r y i n a reset c o n d i t i o n , and a l s o resets a l l
f a u l t c o n d i t i o n s a s s o c i a t e d w i t h t h e turn-around d e l a y c i r c u i t r y . When
"DQI" i s a c t i v e , i t g a t e s t h e "REPLY" s i g n a l through t o form "DELREP" (delayed
r e p l y ) w i t h o n l y a few g a t e d e l a y s .
2.2.2.3
Fault Detection Circuitry
A d e s i g n philosophy was followed which i n c r e a s e s r e l i a b i l i t y and r e d u c e s
f i e l d r e p a i r t i m e . Wherever p o s s i b l e , i n v a l i d c o n d i t i o n s a r e d e t e c t e d and
d i s p l a y e d . For example, t h e "D-FLT" ( d e l a y f a u l t ) s i g n a l i s g e n e r a t e d when
more t h a n one turn-around d e l a y t i m e h a s been s e l e c t e d . T h i s o c c u r r e n c e
i s l o g i c a l l y i m p o s s i b l e , b u t h a s i n f a c t o c c u r r e d due t o bad c h i p s , c o n n e c t o r
problems, and s o f o r t h . Another example shown i s "C-FLT" ( c o u n t e r f a u l t ) .
The 1 3 - b i t c o u n t e r should n e v e r o v e r f l o w , b u t i f i t d o e s a n e r r o r i s i n d i c a t e d .
Two o t h e r f a u l t d e t e c t o r s a r e l o c a t e d on t h e ELR2 c a r d , b u t a r e n o t shown
i n F i g . 9 f o r s i m p l i c i t y . These a r e "REP-FLT" ( r e p l y f a u l t ) , which i s
g e n e r a t e d when any combination of "DAREP" (delayed ATCRBS r e p l y ) , "DDABREP"
(delayed DABS r e p l y ) and a n undelayed r e p l y a r e p r e s e n t s i m u l t a n e o u s l y , and
"MODE-FLT" ( r e p l y mode f a u l t ) , which i s g e n e r a t e d when any combination of
Mode A ATCRBS, Mode C ATCRBS, and DABS f l i p - f l o p s a r e s e t s i m u l t a n e o u s l y .
The "MODE-FLT" s i g n a l t r u e can i n d i c a t e a f a i l u r e i n t h e t r a n s p o n d e r o r a
f a i l u r e i n t h e "MUTUAL SUPPRESSION DRIVER CIRCUITRY" shown i n F i g . 9.
2.2.2.4
ATCRBS Turnaround Delay
2.2.2.4.1
128 Microsecond Delay S e l e c t e d
The "REPLY" and "DIG SUP" ( d i g i t a l s u p p r e s s i o n ) s i g n a l s become a c t i v e ,
which i n t u r n set t h e "START" s i g n a l a t t h e n e x t r i s i n g edge of t h e "2MHz
CLOCK". The "START" s i g n a l d r i v e s t h e "MUT SUP" (mutual s u p p r e s s i o n ) l i n e
t o t h e t r a n s p o n d e r , t h e r e b y i n h i b i t i n g f u r t h e r decoding of i n t e r r o g a t i o n s w h i l e
the delay is taking place.
The s t a t e of t h e "MODE-A" and "MODE-C" s i g n a l s i s t h e n l a t c h e d a t t h e n e x t
r i s i n g edge of t h e 2MHz c l o c k . No more t h a n one of t h e s e s i g n a l s should b e
t r u e . Meanwhile, t h e "REPLY" s i g n a l from t h e t r a n s p o n d e r i s simply g a t e d o u t ,
and no delayed r e p l y i s g e n e r a t e d a s y e t . 125 microseconds l a t e r , t h e "END125"
s i g n a l i s g e n e r a t e d and g a t e d w i t h t h e t r u e "D128" s i g n a l t o produce a s i g n a l
c a l l e d "SET".
The "SET" s i g n a l s e n d s t h e "SET-A" and SET-C" s i g n a l s t o t h e
t r a n s p o n d e r , c a u s i n g t h e t r a n s p o n d e r t o g i v e an a p p r o p r i a t e Mode A o r Mode C
ATCRBS r e p l y 3 microseconds l a t e r . T h i s r e p l y i s g a t e d through t h e system t o
form "DAREP" (delayed ATCRBS r e p l y ) , because t h e "SET" s i g n a l sets a f l i p - f l o p
which a l l o w s t h i s t o o c c u r . Thus t h e t r a n s p o n d e r h a s a c t u a l l y g e n e r a t e d two
ATCRBS r e p l i e s : t h e f i r s t i s l o s t , and t h e second one (which comes 128 micro-
s e c o n d s a f t e r t h e f i r s t r e p l y ) i s t r a n s m i t t e d as t h e d e l a y e d r e p l y . A s h o r t
w h i l e l a t e r (157 m i c r o s e c o n d s a f t e r "START" g o e s t r u e ) , t h e "END 157"
s i g n a l becomes a c t i v e , which r e t u r n s t h e c i r c u i t r y t o i t s i n i t i a l s t a t e by
g e n e r a t i n g t h e "DONE" s i g n a l .
2.2.2.4.2
256 Microsecond Delay S e l e c t e d
The same s e q u e n c e of e v e n t s o c c u r s as o c c u r r e d w i t h t h e 1 2 8 microsecond
ATCRBS d e l a y , e x c e p t t h a t "END 253" i s used t o e l i c i t t h e second ATCRBS r e p l y
from t h e t r a n s p o n d e r and "END 285" i s u s e d t o reset t h e d e l a v c i r c u i t r y .
2.2.2.5
.
DABS Turnaround Delay
The DABS t u r n a r o u n d d e l a y i s h a n d l e d i n a n e n t i r e l y d i f f e r e n t manner
from t h e ATCRBS d e l a y . T h i s i s d u e t o t h e d i f f e r e n t t i m i n g schemes i n v o l v e d
(690 KHz c l o c k f o r ATCRBS v s . 1 MHz c l o c k f o r DABS r e p l i e s ) . Note t h a t ATCRBS/
DABS a l l - c a l l r e p l i e s are c o n s i d e r e d t o b e "DABSt'-type r e p l i e s i n s o f a r as t h e
timing i s concerned.
2.2.2.5.1
1 2 8 Microsecond Delay S e l e c t e d
The f i r s t r e p l y p u l s e and d i g i t a l s u p p r e s s i o n s i g n a l s are used t o g e n e r a t e
"START", as was t h e c a s e w i t h ATCRBS. 256 m i c r o s e c o n d s l a t e r , "END 256" i s used
t o g e n e r a t e t h e "DONE" s i g n a l which resets t h e d e l a y c i r c u i t r y . The "DABS XMIT"
(DABS t r a n s m i s s i o n ) s i g n a l g o e s t r u e p r i o r t o t h e "REPLY" s i g n a l .
"DABS XMIT" i s l a t c h e d , and "DABS.L1' i s u s e d t o g a t e t h e DABS r e p l y i n t o
a CMOS s h i f t r e g i s t e r c h a i n where i t i s d e l a y e d f o r 1 2 8 m i c r o s e c o n d s . When
t h e DABS r e p l y emerges from t h e s h i f t r e g i s t e r d e l a y , i t becomes "DDABREP"
( d e l a y e d DABS r e p l y ) and i s s e n t o u t t o t h e t r a n s m i t t e r as t h e d e l a y e d r e p l y .
2.2.2.5.2
256 Microsecond Delay S e l e c t e d
Operation is s i m i l a r t o t h a t described i n t h e preceding paragraph, except
t h a t more s h i f t r e g i s t e r s are u s e d t o o b t a i n a l o n g e r d e l a y and "END 384" i s
used t o reset t h e d e l a y l o g i c a f t e r c o m p l e t i o n of t h e DABS r e p l y .
2.2.3
ELR3 Card
The l o g i c c o n t a i n e d on t h i s c a r d a l l o w s a message t u r n - a r o u n d test t o b e
performed between t h e s e n s o r and CPME. It a l s o a l l o w s t h e CPME t o r e p o r t i t s
o p e r a t i n g s t a t u s t o t h e s e n s o r f o r r e m o t e d i a g n o s i s of CPME problems.
2.2.3.1
Initialization
The "RESET" s i g n a l c o m p l e t e l y c l e a r s t h e SM p r o c e s s o r , and a l l f a u l t cond i t i o n s a s s o c i a t e d w i t h i t . A f t e r e v e r y SM i n t e r f a c e t r a n s a c t i o n , t h e s y s t e m
i s c l e a r e d ( w i t h t h e e x c e p t i o n of PBUT, B-bit, and f a u l t c o n d i t i o n s ) by t h e
"SMCLR" ( s t a n d a r d message c l e a r ) s i g n a l . The "SMCLR" s i g n a l becomes a c t i v e
220 microseconds a f t e r t h e f i r s t l e a d i n g edge of "SMC" ( s t a n d a r d message
c l o c k ) , and s o o c c u r s a f t e r a l l SM i n t e r a c t i o n s have t a k e n p l a c e . R e f e r t o
t h e s i m p l i f i e d s c h e m a t i c p r e s e n t e d i n F i g . 10.
2.2.3.2
Operation
The t r a n s p o n d e r h a s a u n i - d i r e c t i o n a l c l o c k l i n e o u t p u t , "SMC", which
.
p r o v i d e s t h e r e q u i r e d t i m i n g f o r t h e i n t e r f a c e . The t r a n s p o n d e r a l s o p r o v i d e s
a 1 - b i t b i - d i r e c t i o n a l d a t a b u s , "SMD" ( s t a n d a r d message d a t a ) , on which u p l i n k
d a t a i s t r a n s f e r r e d from t h e t r a n s p o n d e r t o t h e SMI p r o c e s s o r , and downlink
d a t a i s s e n t t o t h e t r a n s p o n d e r from t h e SMI p r o c e s s o r . The o p e r a t i o n of t h e
SMI p r o c e s s o r i s summarized i n t h e f l o w c h a r t of F i g . 11.
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3.0
ENVIRONMENTAL SYSTEM
The environmental system shown in Fig. 12 enables the CPME to operate
satisfactorily outdoors. All temperature switches are located on a single
heat sink, which senses the CPME's internal air temperature. The safe operating
limits on this internal air temperature are shown in Fig. 13.
Each CPME system has been tested and shown to be completely functional
over outside air temperatures ranging from -lO°F to +105OF. When operated
in the high-power mode, the CPME's internal air temperature is typically
80°F when'the outside ambient is -lO°F.
Operation in the high temperature range is limited by the transponder
(maximum transponder operating temperature is +130°F) and by the efficiency
of the heat exchanger. The heat exchanger limits the transponder's temperature
to a rise of 25OF.aboveoutside ambient when the CPME is in the high-power
mode, and 18OF in the low-power mode. Thus the CPME can safely operate outdoors in temperatures of 105OF for the high-power mode and 112OF for the lowpower mode.
500 w
HEATER
SAFETY BflCK- UP
SWITCH:
OPEN ABOVE
113°F
I
ATC-89(12)
1
OPEN ABOVE
90°F
It LAT
LXCHANOER
OUTSIDE
(COOUUG)
FANS
HEAT
EXCHANGER
INCIDE
(CI KOLATJUG)
FANS
EXTRA CIRCULATlNG
FANS INSIDE CPME
CLOSED ABOVE
OPEN ABOVF
)--0
Fig. 12.
TO STATUS
h REPORTING
(FAULT)
LOGIC
UNDER-TEMP
Environmental controls
I
CPME Internal A i r Temp.
Maximum: 1 3 0 ° F
I
OVER-TEMP FAULT
120
HEAT EXCHANGER'S
COOLING FANS ON
90
80
70
60
50
Minimum:
40°F
F i g . 13.
Thermal operating c h a r a c t e r i s t i c
4.0
POWER DISTRIBUTION
4.1
Over-voltage P r o t e c t i o n
A l l CPME s u p p l i e s w i t h t h e e x c e p t i o n of t h e l O O O V s u p p l y are equipped
w i t h o v e r - v o l t a g e p r o t e c t i o n . A d d i t i o n a l l y , t h e CPME i s p r o t e c t e d from
power l i n e t r a n s i e n t s .
A l l s u p p l i e s h a v e a c c e s s i b l e v o l t a g e a d j u s t m e n t s , e x c e p t f o r t h e +12V
and -12V s u p p l i e s which are n o n - a d j u s t a b l e .
The +5V and +28V h a v e been
f i t t e d w i t h knobs f o r ease of a d j u s t m e n t . The +6V, -20V, and +1000V s u p p l i e s
are s c r e w d r i v e r a d j u s t a b l e . The p l e x i g l a s s h i g h v o l t a g e p r o t e c t i o n p l a t e
must b e removed b e f o r e t h e v o l t a g e a d j u s t m e n t t r i m p o t on t h e +1000V s u p p l y
c a n b e r e a c h e d , s o c a r e s h o u l d b e t a k e n when making t h i s a d j u s t m e n t .
4.2
C i r c u i t Breakers
T h r e e c i r c u i t b r e a k e r s w i t c h e s are p r o v i d e d . A 2.5 amp b r e a k e r c o n t r o l s
t h e "convenience o u t l e t " ; a 1 0 amp b r e a k e r c o n t r o l s t h e power t o t h e 500 w a t t
h e a t e r and t o a l l f a n s , and a s p e c i a l 7 . 5 amp b r e a k e r c o n t r o l s power t o t h e
l o g i c and RF components. The 7.5 amp b r e a k e r f e a t u r e s immunity t o c u r r e n t
This feature
s p i k e s which are o f t e n e n c o u n t e r e d d u r i n g s y s t e m power-up.
was r e q u i r e d s o t h a t i f , d u r i n g normal f i e l d o p e r a t i o n , AC power t o t h e CPME
i s i n t e r r u p t e d , when power i s r e s t o r e d t h e CPME w i l l power-up a g a i n n o r m a l l y
w i t h o u t t h e need t o reset t h e b r e a k e r by human i n t e r v e n t i o n . N o t i c e t h a t
t h e t o t a l c u r r e n t which c o u l d b e drawn from t h e AC power l i n e i s 2.5
7.5
+ 1 0 = 20 amperes, t h u s s t a n d a r d s e r v i c e c a n b e used.
+
4.3
Power Consumption
A c t u a l power t a k e n by t h e CPME from t h e AC l i n e i s as f o l l o w s .
a.
E n v i r o n m e n t a l System:
The h e a t e r u s e s 500 w a t t s , and t h e h e a t e x c h a n g e r ' s c o o l i n g f a n s u s e 50 w a t t s .
b.
RF, L o g i c , and C i r c u l a t i n g F a n s :
The low-power mode u s e s 240 w a t t s , w h i l e t h e high-power mode u s e s 325 w a t t s .
Note t h a t t h e s e f i g u r e s are t h e "heat l o a d " which t h e h e a t e x c h a n g e r i s r e q u i r e d
to dissipate.
c.
Worst Combination:
The w o r s t c a s e power consumption o c c u r s on c o l d d a y s when t h e CPME i s
i n t h e high-power mode, r e q u i r i n g 325 w a t t s ( e l e c t r o n i c s and c i r c u l a t i n g f a n s )
p l u s 500 w a t t s ( h e a t e r ) o r a t o t a l of 825 w a t t s drawn from t h e AC power l i n e s .
Acknowledgments
The development of the DABS CPME took place under the guidance of
R.R. LaFrey and J.D. Welch, MIT/Lincoln Assistant Group Leaders, System
Design and Evaluation. Significant contributions to the design,construction,
and checkout of the CPME were made by E.A. Crocker, J.L. Cataldo, A. Augustine,
W.J. Grabowski, B.F. Adams, and B. Hutchings. The helpful suggestions regarding
construction and thermal design given by R.G. Nelson and D.M. Nathanson are
also gratefully acknowledged.
APPENDIX A
TABLE OF CONTENTS
Page
1.0
2.0
........................
1.1 S e t C a l l S i g n . . . . . . . . . . . . . . . . . . . . . . .
1 . 2 SetATCRBSModeCCode . . . . . . . . . . . . . . . . . .
1 . 3 S e t ATCRBS Mode A Code . . . . . . . . . . . . . . . . . .
1.4 . S e t Receiver Threshold . . . . . . . . . . . . . . . . . .
1 . 5 S e l e c t O p e r a t i n g Modes . . . . . . . . . . . . . . . . . .
1 . 6 S e t AT5 . . . . . . . . . . . . . . . . . . . . . . . . . .
1 . 7 Powerup . . . . . . . . . . . . . . . . . . . . . . . . . .
1 . 8 Check S u p p l i e s . . . . . . . . . . . . . . . . . . . . . .
1 . 9 Check CPME C o n t r o l P a n e l I n d i c a t o r s . . . . . . . . . . . .
1 . 1 0 A d j u s t AT1 . . . . . . . . . . . . . . . . . . . . . . . .
1.11 Turn On Environmental System . . . . . . . . . . . . . . .
1 . 1 2 S e t PAM/PPM S w i t c h . . . . . . . . . . . . . . . . . . . .
USE OF CPME DURING MONOPULSE ACCURACY TESTS . . . . . . . . . .
2 . 1 E x t e r n a l S i g n a l Source . . . . . . . . . . . . . . . . . .
2.2 C o n n e c t i n g t h e E x t e r n a l S o u r c e . . . . . . . . . . . . . .
2 . 3 Example of CPME U s e f o r C a l i b r a t i o n . . . . . . . . . . . .
NORMALOPERATION
APPENDIX A
CPME OPERATING PROCEDURES
1.0 NORMAL OPERATION
It is assumed that the CPMX has been set up so that ample space is available
all around the unit (to facilitate ventilation and repairs) and that if the
unit is located outdoors, the sun shield has been attached. It is also assumed
that the CPME unit has been connected to 120 VAC 20 ampere service.
1.1 Set Call Sign
The CPME will transmit a Comm-B reply with a dummy call sign contained in
the extended capability MB field in response to a correctly addressed interrogation with RL=1 and MSRC=0001. The call sign consists of 42 bits which are
transmitted in bit positions 47 through 88 of the Corn-B data field inclusive
(see FAA-RD-74-62, paragraph 4.4.3.6).
Set the 42-bit call sign as follows:
1.1.1 Remove board 83 (ELR3) from the "External Logic Rack"
Fig. A-1)
.
(see
1.1.2 Set call-sign switches as follows (switch set "ON" transmits
a "ZERO", "OFF" transmits a "ONE") :
Bit
/I
47
48
49
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
Pack Location
U58
u12
u12
u12
u12
u12
u12
u12
u12
U24
U24
U24
U24
U24
U24
U24
U24
U36
U36
U36
U36
U36
Switch d
1
2
1
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
Pack Location
U36
U36
U36
U48
U48
U48
U48
U48
U48
U48
U48
U60
U60
U60
U60
U60
U60
U60
U60
Switch
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
/I
EXTERNAL
XMT R
SOURCE
PATCH
Fig. A-1.
-
DABS CPME:
I n t e r n a l view
1.1.3 Carefully replace ELR3 board in the proper slot (slot #3)
of the External Logic Rack.
1.2
Set ATCRBS Mode C Code (altitude simulator)
On the CPME CONTROL PANEL locate the two sets of switches marked
"ALTIMETER". The transmitter bits are set as follows (see Fig. A-2):
Bit
Switch Bank
Switch
Left
Left
Left
Left
Left
Left
Left
Right
Right
Right
Right
1
2
3
/I
4
5
6
7
1
2
3
4
Note: Switch set "ON" transmits the bit, switch set "OFF" does not. Bit
Dl is not used (always zero). The zero feet altitude code is obtained by
setting B2, B4, and C2 "ON", all others "OFF".
1.3 Set ATCRBS Mode A Code
CONTROL PANEL.
1.4
on thumbwheel switches provided on CPME
Set Receiver Threshold
Adjust variable attenuator AT2 for the desired threshold level. A setting
of 26 dB results in an input sensitivity of approximately -40 dBm as referenced
to the CPME RF port. Similarly, a setting of 66 dB results in a sensitivity of
approximately fl dBm. It is recommended that attenuator AT2 should always be set
at some value greater than 8 dB for the purpose of protecting the receiver. See
calibration information on each CPME for more accurate setting.
1.5
Select Operating Modes
1.5.1 Select fl, 128, or 256 usec additional turn-around delay
time by setting the TURNAROUND DELAY control (see Fig. A-2).
1.5.2 Set the INITIALIZE/RUN switch to the RUN position. Note:
after powerup, if it is necessary to change the Turnaround Delay setting or
Transmitter Power switch, then put the 1NITIALIZE/RUN switch into the INITIALIZE
position and then back to the RUN position.
3 POSITtON
SELECTOR YNOE
ATCRBS MODE A CODE
\
7
LEFT S W I T C H
RIGUT SWITCH
BANK
\
ALTIMETER
f
0
DELAY
INTERROGATIONS
FAULT
ATCRBS
DABS
LOCKOUTS
@
AU
X
DISCRETE
AORS
- .-
Q
6
AUX
AID
DABS ONLY ALL- CALL
XMTR
PWR
. .- .
Q
ATCRBS
REPORTING TO SENSOR
ALL
LOC KOUT
STATUS
STATE
0
@ 1 KV.6V
ACTIVE
HI-PWR
SE L
12
F i g . A-2.
CPME c o n t r o l p a n e l diagram
0
1 . 5 . 3 S e t t h e TRANSMITTER POWER (XMTR PWR) s w i t c h t o e i t h e r HIGH
o r LOW power, a s d e s i r e d . A t t h e CPME RF p o r t , t h e o u t p u t power i n t h e
low-power mode can be v a r i e d from -80 dBm t o +21 dBm i n 1 dB s t e p s , whereas
o u t p u t power i n t h e high-power mode can be v a r i e d from -9 dBm t o +51 dBm
c o n t i n u o u s l y . For g r e a t e s t a c c u r a c y i n power l e v e l s e t t i n g , i t i s recommended
t h a t t h e high-power mode o u t p u t should be used o n l y i n t h e r a n g e from +11 dBm
t o +51 dBm. It i s a l s o recommended t h a t t h e low-power mode b e used whenever
p o s s i b l e , e s p e c i a l l y during h o t weather.
1 . 5 . 4 S e t t h e s t a t u s REPORTING TO SENSOR s w i t c h e s a s d e s i r e d f o r
s t a t u s r e p o r t s . I n r e s p o n s e t o a c o r r e c t l y a d d r e s s e d i n t e r r o g a t i o n w i t h RL=1
and MSRC=0001, t h e CPME s h a l l t r a n s m i t a Comm-B r e p l y w i t h b i t s 38 through
46 d e f i n e d a s f o l l o w s :
1.5.4.1
A l l z e r o e s i f t h e ALL STATUS s w i t c h i s i n t h e
INHIBIT p o s i t i o n .
1.5.4.2
With t h e ALL STATUS s w i t c h i n t h e ENABLE p o s i t i o n
and t h e LOCKOUT STATE s w i t c h i n t h e INHIBIT p o s i t i o n , t h e CPME f a u l t b i t s
( d e f i n e d i n p a r a g r a p h 1.9.5.2) a r e t r a n s m i t t e d i n b i t s 38 through 42
i n c l u s i v e . B i t s 43 t h r o u g h 46 i n c l u s i v e a r e t r a n s m i t t e d a s z e r o e s .
1 . 5 . 4 . 3 With t h e ALL STATUS s w i t c h i n t h e ENABLE p o s i t i o n
and t h e LOCKOUT STATE s w i t c h i n t h e ENABLE p o s i t i o n , t h e CPME f a u l t b i t s a r e
t r a n s m i t t e d i n b i t s 38 through 42, and t h e CPME l o c k o u t s t a t e s t a t u s ( d e f i n e d
i n paragraph 1 . 9 . 4 ) i s r e p o r t e d i n b i t s 43 through 46.
1.5.4.4
Whenever t h e ALL STATUS s w i t c h i s i n t h e ENABLE
p o s i t i o n , t h e FR b i t ( b i t 1 9 of any s u r v e i l l a n c e o r Comm-B r e p l y ) i s t r a n s m i t t e d a s a "one" i f any of t h e f a u l t b i t s a r e s e t ( l o g i c a l "OR") and "zero"
o t h e r w i s e . When t h e ALL STATUS s w i t c h i s i n t h e INHIBIT p o s i t i o n , t h e FR b i t
i s a "zero".
1.6
S e t AT5
A t t e n u a t o r AT5 d i r e c t l y c o n t r o l s t h e o u t p u t power i n t h e low-power mode.
S e t t o 11 dB f o r normal low-power mode o p e r a t i o n , t h u s g i v i n g a p p r o x i m a t e l y
+10 dBm o u t p u t a t t h e CPME RF p o r t . See c a l i b r a t i o n i n f o r m a t i o n on each CPME
f o r more a c c u r a t e s e t t i n g . I n t h e high-power mode, AT5 sets t h e d r i v e l e v e l
t o t h e RF power amp. S e t AT5 t o 6 dB f o r normal high-power mode o p e r a t i o n ,
t h u s g i v i n g +10 dBm i n p u t t o t h e GE RF power amp.
1.7
Powerup
1.7.1
Make s u r e a l l c i r c u i t b r e a k e r s a r e i n t h e OFF p o s i t i o n .
1.7.2 Connect antenna system c a b l e t o t h e type N connector on
t h e o u t s i d e of t h e CPME.
1 . 7 . 3 Connect AC power (110 VAC, 20 A) t o t h e CPME through t h e
Bendix c o n n e c t o r , on t h e o u t s i d e of t h e e n c l o s u r e , u s i n g t h e power cord
provided.
position.
1.7.4 Turn t h e c i r c u i t b r e a k e r marked "RF/LOGIC" t o t h e ON
The handle should l i g h t up r e d .
1.7.5
The green.lamp on t h e o u t s i d e of t h e CPME e n c l o s u r e should
l i g h t up.
Turn t h e ON/OFF s w i t c h of t h e DVM t o t h e ON p o s i t i o n . Check t h e s u p p l i e s
by s e t t i n g t h e D V M f s s e l e c t o r s w i t c h t o t h e d e s i r e d supply and r e a d i n g t h e
v a l u e on t h e D i g i t a l Volt Meter (DVM). The DVM i s a c c u r a t e t o about 2%. Note
t h a t t h e 6V and lOOOV s u p p l i e s a r e a c t i v e o n l y when t h e high-power t r a n s m i t t e r
has been s e l e c t e d . Also n o t e t h a t t h e 6V supply has been s e t t o about 5.8V.
T h i s lower f i l a m e n t v o l t a g e i n c r e a s e s t h e l i f e expectancy of t h e GE RF power
amp, and t h e v o l t a g e can be i n c r e a s e d a s t h e tube ages. Turn o f f t h e DVM.
1.9
Check CPME C o n t r o l Panel I n d i c a t o r s
1 . 9 . 1 Turnaround d e l a y i n d i c a t o r should correspond t o s e l e c t e d
turn-around d e l a y . I f n o t , t h e n r e - i n i t i a l i z e t h e system u s i n g t h e
INITIALIZE/RUN switch.
1 . 9 . 2 I f t h e high-power mode i s s e l e c t e d , then t h e " l K V , 6V
ACTIVE" and "HI-PWR XMTR SEL" i n d i c a t o r s should be l i t . I f t h e low-power
mode i s s e l e c t e d , n e i t h e r of t h e s e should be l i t . R e - i n i t i a l i z e t h e system
i f necessary.
1 . 9 . 3 The ATCRBS INTERROGATIONS i n d i c a t o r f l a s h e s momentarily
( . l s e c ) when a n ATCRBS i n t e r r o g a t i o n i s d e t e c t e d . The DABS INTERROGATIONS
i n d i c a t o r i s a c t i v a t e d when a DABS i n t e r r o g a t i o n i s d e t e c t e d , and remains
l i t f o r approximately 16 seconds t h e r e a f t e r . No v i s u a l i n d i c a t i o n i s given
f o r ATCRBS/DABS o r DABS-only All-Calls.
1 . 9 . 4 The "LOCKOUTS" i n d i c a t o r s r e f l e c t t h e s t a t e of t h e CPME
When t h e ALL
l o c k o u t s a t a l l times.
I n d i c a t o r l i t i m p l i e s "locked out".
STATUS and LOCKOUT STATE s w i t c h e s a r e b o t h i n t h e ENABLE p o s i t i o n , t h e n t h e
l o c k o u t s t a t e a s i n d i c a t e d i s t r a n s m i t t e d i n a Comm-B r e p l y a s f o l l o w s ( i n
r e s p o n s e t o a c o r r e c t l y a d d r e s s e d i n t e r r o g a t i o n w i t h RL=1 and MSRC=0001):
Bit
Bit
Bit
Bit
43:
44:
45:
46:
1.9.5
ATCRBS l o c k o u t s t a t e
ATCRBSIDABS A l l - C a l l l o c k o u t s t a t e
a u x i l i a r y (DABS-only) A l l - C a l l l o c k o u t s t a t e
a u x i l i a r y d i s c r e t e address i n t e r r o g a t i o n lockout s t a t e
Fault B i t s
1 . 9 . 5 . 1 I f a CPME f a u l t e x i s t s , t h e LED marked "FAULT"
w i l l l i g h t up and s o w i l l t h e r e d " f a u l t lamp" on t h e o u t s i d e of t h e CPME
e n c l o s u r e . T h i s main " f a u l t b i t " i s a l o g i c a l OR of t h e f a u l t b i t s l i s t e d
below. It i s t h e s t a t e of t h i s main f a u l t b i t which i s t r a n s m i t t e d a s t h e FR
b i t i n r e p l i e s , a s n o t e d i n p a r a g r a p h 1.5.4.4.
The f a u l t l i g h t s a r e l i t
r e g a r d l e s s of t h e s t a t e of t h e "Reporting t o Sensor" s w i t c h e s .
1.9.5.2
F i v e LEDS (#I-#5) on t h e CPME C o n t r o l P a n e l
always d i s p l a y t h e s t a t e of t h e CPME f a u l t d e t e c t i o n system. I f t h e
"Reporting t o Sensor: A l l S t a t u s " s w i t c h i s i n t h e ENABLE p o s i t i o n , t h e n
t h e c o n d i t i o n of t h e s e LEDS i s t r a n s m i t t e d i n t h e Comm-B r e p l y b i t s shown
( s e e a l s o p a r a g r a p h 1.5.4.2) i n r e s p o n s e t o a c o r r e c t l y a d d r e s s e d i n t e r r o g a t i o n w i t h RL-1 and MSRC=0001.
LED /I
Reply B i t
1
2
38
39
3
4
5
40
41
42
Fault
O s c i l l a t o r o u t of phase-lock.
Power f a i l l i n i t i a l i z e ( a 128 s e c
t i m e r which i s a c t i v a t e d a t powerup
o r when system i s i n i t i a l i z e d ) .
I n s i d e of e n c l o s u r e under-temperature.
I n s i d e of e n c l o s u r e over-temperature.
M i s c e l l a n e o u s f a u l t ( a l o g i c a l OR of
t h e f a u l t conditions described i n
paragraph 1.9.5.3).
1 . 9 . 5 . 3 M i s c e l l a n e o u s f a u l t c o n d i t i o n s a r e d e t e c t e d and
d i s p l a y e d a s f o l l o w s ( t h e s e b i t s a r e n o t i n d i v i d u a l l y t r a n s m i t t e d i n any
replies) :
LED fl
6
7
8
9
Fault
T r a n s m i t t e r d u t y c y c l e exceeded.
M u l t i p l e turn-around d e l a y s s e l e c t e d .
Multiple reply types detected.
M u l t i p l e re1 l y modes r e q u e s t e d ( a
transponder f a u l t condition)
Turnaround d e l a y s t a t e c o u n t e r f a i l u r e .
SMI s t a t e c o u n t e r f a i l u r e .
SPARE f unused)
.
1.10 Adjust AT1
I f t h e high-power mode i s s e l e c t e d , t h e CPME RF power o u t p u t l e v e l i s
a d j u s t e d by a t t e n u a t o r AT1. To a d j u s t t h i s , monitor t h e r e p l i e s by c o n n e c t i n g
an o s c i l l o s c o p e t o t h e "OUTPUT MONITOR TO SCOPE" j a c k provided. Convert
t h e peak v o l t a g e r e a d i n g s of t h e r e p l y p u l s e s t o "dBm" r e a d i n g s by u s i n g
t h e c r y s t a l c a l i b r a t i o n c h a r t s provided w i t h each CPME. Add t h i s power r e a d i n g
( i n dBm) t o t h e " b i a s v a l u e " ( s e e c a l i b r a t i o n i n f o r m a t i o n f o r each CPME),
which i s about +38.5 dB, t o o b t a i n t h e a c t u a l RF o u t p u t power a t t h e CPME RF
p o r t . A c a l i b r a t i o n c h a r t which c o n v e r t s t h e d i a l r e a d i n g of AT1 i n t o t h e
a t t e n u a t i o n v a l u e i s a l s o p r o v i d e d , s o t h a t r e l a t i v e power l e v e l s c a n b e
easily set.
1.11 Turn On Environmental System
Turn on t h e c i r c u i t b r e a k e r marked "HEAT/COOLH.
f a n s should r u n c o n t i n u o u s l y .
A l l f i v e of t h e i n t e r n a l
1.12 S e t PAM/PPM Switch
A s c r e w d r i v e r - a d j u s t s w i t c h i s l o c a t e d on t h e f r o n t of t h e t r a n s p o n d e r f o r
t h e purpose of changing r e p l y modulation formats. The CPME i s shipped w i t h t h e
s w i t c h i n t h e PPM p o s i t i o n , and t h e c o n t r o l should normally remain i n t h i s
position.
2.0
USE OF CPME DURING MONOPULSE ACCURACY TESTS
2.1
E x t e r n a l S i g n a l Source
A high-accuracy CW s i g n a l s o u r c e , such a s a n HP8640B s i g n a l g e n e r a t o r ,
i s required.
2.2
Connecting t h e E x t e r n a l Source
Connect t h e e x t e r n a l s o u r c e a s f o l l o w s :
2.2.1
I f t h e power a v a i l a b l e from t h e s i g n a l g e n e r a t o r i s +20 dBm,
t h e n set i t t o t h i s v a l u e . With t h e CPME power OFF, remove t h e " E x t e r n a l XMTR
Source Patch" s e m i - r i g i d c o a x i a l jumper.
Care must be t a k e n i n removing t h i s
jumper s o a s n o t t o damage i t . To remove, unscrew each s i d e by one t u r n ,
t h e n r e p e a t ( a l t e r n a t i n g s i d e s ) u n t i l jumper comes o f f . To r e p l a c e i t , a
t o r q u e wrench i s recommended. A t t a c h t h e s i g n a l g e n e r a t o r t o t h e s i d e of
t h e p a t c h i n p u t marked "XMTR Source Input".
Terminate t h e p a t c h j a c k marked
" I n t e r n a l Source Output" i n a 50 ohm impedance. The CPME can now o p e r a t e
a s b e f o r e , i n e i t h e r h i g h o r low power mode, b u t w i t h a v a r i a b l e frequency
output.
S e t a t t e n u a t o r AT5 t o z e r o dB i f t h e high-power mode i s used.
2.2.2
I f t h e power a v a i l a b l e from t h e s i g n a l g e n e r a t o r i s o i l y
+10 dBm, t h e n set i t t o t h i s v a l u e . With t h e CPME power OFF, remove t h e f l e x i b l e
c o a x i a l c a b l e from pad AT3, l e a v i n g t h e o t h e r end of t h i s c a b l e a t t a c h e d t o t h e
t u b e a m p l i f i e r u n i t . A t t a c h t h e s i g n a l g e n e r a t o r t o t h e c a b l e . The CPME can
now o p e r a t e a s b e f o r e , b u t o n l y i n t h e high-power mode.
2.3
Example of CPME Use f o r C a l i b r a t i o n
Assume t h a t a CPME i s l o c a t e d 7000 f e e t from a s e n s o r . A 200 f o o t c a b l e
( w i t h 6 dB l o s s ) i s used between t h e CPME and t h e 14 dB g a i n horn a n t e n n a ,
g i v i n g a n e f f e c t i v e CPME antenna system g a i n of +8 dB. Also assume a s e n s o r
w i t h a +28 dB g a i n a n t e n n a (ASR-7) and 5 dB e l e v a t i o n l o s s due t o a n t e n n a beam
s h a p i n g , t h u s g i v i n g a n e f f e c t i v e s e n s o r a n t e n n a g a i n of +23 dB.
2.3.1
Link C a l c u l a t i o n
An e s t i m a t e of t h e power l e v e l s involved i s made i n t h e f o l l o w i n g example
( s e e a l s o s e c t i o n 3.5.6.1.3 of t h e DABS CPME Performance S p e c i f i c a t i o n ) . A
maximum power i n p u t of -24 dBm i s r e q u i r e d a t t h e s e n s o r RF p o r t ( s e e FAA-ER-240-26,
p a r a g r a p h 4.5.4.3.1).
W e wish t o know t h e RF power o u t p u t a t t h e CPME RF p o r t
needed t o accomplish t h i s . T h i s i s g i v e n by:
P
o u t , CPME
'in,
sensor
+
197
+
-
-
20 l o g (Range x F r e q ) ]
GHOW
-
GASR7.
FREE SPACE LOSS
Substituting :
P
o u t , CPME
= -24 dBm
+
97
+
7000
20 l o g [ ( -)
5280
(1.090)]
-
8
-
23 = +45 dBm.
Thus a maximum power o u t p u t of +45 dBm i s r e q u i r e d a t t h e CPME RF p o r t t o
produce a s i g n a l l e v e l of -24 dBm a t t h e s e n s o r RF i n p u t p o r t , under t h e s t a t e d
c o n d i t i o n s . The minimum CPME power s e t t i n g r e q u i r e d i s 40 dB less, o r +5 dBm
o u t p u t a t t h e CPME RF p o r t .
2.3.2
CPME U s e
Assume t h e c o n d i t i o n s d e s c r i b e d i n p a r a g r a p h 2.3.1 s t i l l h o l d . Also
assume t h a t a n HP8640B s i g n a l g e n e r a t o r , which h a s +10 dBm o u t p u t , i s used.
Connect t h i s s o u r c e a s d e s c r i b e d i n s e c t i o n 2.2.2, and t u r n t h e CPME on i n
high-power mode. To t a k e t h e f i r s t set o f r e a d i n g s , set t h e frequency of t h e
g e n e r a t o r t o 1090 MHz and monitor r e p l i e s on t h e CPME's "Output Monitor t o Scope"
(built-in c r y s t a l detector*).
Adjust t h e high-power a t t e n u a t o r , AT1, u n t i l t h e
power o u t p u t a t t h e CPME RF p o r t i s +35 dBm (which should r e s u l t i n a -24 dBm
s i g n a l a t t h e s e n s o r ) . To d e t e r m i n e t h e CPME RF p o r t o u t p u t from t h e c r y s t a l
d e t e c t o r r e a d i n g , f i r s t s u b t r a c t t h e "Power B i a s Value" ( t y p i c a l l y 38.5 dB)
from t h e d e s i r e d RF power o u t p u t . I n t h i s example, a power l e v e l of +45 dBm
- 38.5 dB = +6.5 dBm must occur a t t h e c r y s t a l d e t e c t o r . U s e t h e c r y s t a l
c a l i b r a t i o n c h a r t t o c o n v e r t t h i s dBm r e a d i n g t o a v o l t a g e r e a d i n g . For example,
CPME /I1 (which c o n t a i n s c r y s t a l /I4 and AT1 s e r i a l /I13) would b e g i v i n g r e p l i e s
a t a +45 dBm l e v e l i f t h e peak v o l t a g e measured a t t h e o u t p u t monitor was 190 mV.
(which c o r r e s p o n d s t o a +6.5 dBm s i g n a l t o t h e c r y s t a l ) . The s e t t i n g of AT1
should be a b o u t 5 dB a t t h i s p o i n t (which i s a d i a l r e a d i n g of 28 on t h e t u r n s c o u n t i n g d i a l of AT1). For f u r t h e r i n f o r m a t i o n , r e f e r t o t h e DABS CPME System
Block Diagram.
Once t h e s e n s o r i s c a l i b r a t e d a t t h i s s e t t i n g , change t h e HP8640B frequency
+3
MHz,
a s s p e c i f i e d i n t h e t e s t p r o c e d u r e s . Now d i a l i n 5 dB a d d i t i o n a l
a t t e n u a t i o n on AT1 and r e p e a t (you can a g a i n monitor t h e RF power o u t p u t on t h e
c r y s t a l d e t e c t o r t o make s u r e t h e l e v e l went down by 5 dB). Continue t h e procedure
u n t i l t h e l o w e s t r e q u i r e d power s e t t i n g h a s been r e a c h e d , changing t h e frequency
n i n e t i m e s a t each of t h e n i n e power s e t t i n g s , f o r a t o t a l of 8 1 s e n s o r r u n s .
*Note:
To u s e t h e b u i l t - i n c a l i b r a t e d c r y s t a l d e t e c t o r , r u n a s h o r t BNC c a b l e
from t h e "Output Monitor t o Scope" j a c k t o a 1-Megohrn scope i n p u t . -Do n o t
t e r m i n a t e -t h e c a b l e , a s t h e d e t e c t o r i s a l r e a d y t e r m i n a t e d i n s i d e t h e CPME.
APPENDIX B
EXCEPTIONS AND CLARIFICATIONS TO
CALIBRATION AND PERFORMANCE MONITOR EOUIPMENT (CPME)
ENGINEERING REQUIREMENT, FAA-ER-240-29*
T h i s Appendix p r o v i d e s a paragraph-by-paragraph l i s t i n g of ways i n which
t h e C a l i b r a t i o n and Performance Monitor Equipment d e s c r i b e d i n t h i s p r o j e c t
r e p o r t d e v i a t e from FAA E n g i n e e r i n g Requirement FAA-ER-240-29".
Items are
a l s o i n c l u d e d t o c l a r i f y t h e i n t e n d e d meaning of a r e q u i r e m e n t o r t h e manner
i n which t h e r e q u i r e m e n t was m e t i n t h e MITILincoln L a b o r a t o r y CPME d e s i g n .
Many of t h e l i s t e d d e v i a t i o n s d e r i v e from t h e f o l l o w i n g agreed-upon ER
e x c e p t i o n s upon which t h e d e s i g n of t h e MIT/Lincoln L a b o r a t o r y - p r o v i d e d CPMEs
was b a s e d :
*A s
(1)
The LL CPME s h a l l have no ~omm-C/Comm-D c a p a b i l i t y , h e n c e no
ELM c a p a b i l i t y . A l s o , any r e p l y b i t s w h i c h , when " t r u e " ,
i n d i c a t e ELM c a p a b i l i t y s h a l l b e set " f a l s e " .
(2)
The LL CPME s h a l l n o t respond t o Mode 2 i n t e r r o g a t i o n s .
(3)
The LL CPME s h a l l have a h i g h power mode.
(4)
S p e c i f i c a t i o n FAA-G-2100
goal.
s h a l l be considered t o be a design
amended by Amendment 1 and S p e c i f i c a t i o n Change 1 d a t e d 20 May 1976.
..
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7
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Page
6
Para. No.
Reason f o r Change
3.5.1.4
Revised and
Reworded
Change
D e l e t e f i r s t s e n t e n c e and s u b s t i t u t e : "The CPME s h a l l n o t r e p l y
t o DABS u p l i n k t r a n s m i s s i o n s i n which a sync phase r e v e r s a l i s
n o t d e t e c t e d i n t h e a s s i g n e d i n t e r v a l , a s s p e c i f i e d i n paragraph
2.4.5 of FAA-RD-74-62. "
I n second s e n t e n c e change "95 p e r c e n t " t o "90 p e r c e n t " .
7
3.5.1.8
Correction
In third l i n e delete "(squitter)".
8
Table
3.5.2-1
Correction
I n t a b l e c a p t i o n change "DABS" t o "ATCRBS~DABS'~.
8
3.5.2.2
Added r e q u i r e ment
Add, a f t e r "as d e s c r i b e d i n FAA-RD-74-62," S e c t i o n 4.4.3.1, which
i s summarized i n Table 3.5.2-2.
The commands shown i n t h e t a b l e
a r e b i t s 3 , 4 , and 5 of an u p l i n k s u r v e i l l a n c e o r Comm-A i n t e r r o g a t i o n . "X" i n d i c a t e s a "don't c a r e " c o n d i t i o n . Command 011 i s
unassigned. The I T b i t ( B i t 3) i s 1 i f t h e i n t e r r o g a t i o n comes from
a s t a n d a r d i n t e r r o g a t o r and 0 i f t h e i n t e r r o g a t i o n comes from a n
a u x i l i a r y i n t e r r o g a t o r . The l o c k o u t s t a t e s a r e g i v e n a s 1 =
locked o u t , 0 = n o t locked o u t . "standard" A l l - C a l l s a r e ATCRBS/DABS
All-Calls.
A u x i l i a r y A l l - C a l l s a r e DABS-only A l l - C a l l s w i t h IT=O.
DABS-only All-Calls w i t h I T = 1 cannot be locked o u t . For example,
i f t h e CPME i s locked o u t t o A u x i l i a r y A l l - C a l l s b u t not t o s t a n d a r d
A l l - C a l l s nor A u x i l i a r y D i s c r e t e i n t e r r o g a t i o n s ( l o c k o u t s t a t e 0 1 0 ) ,
and a n i n t e r r o g a t i o n w i t h b i t s 3, 4 , and 5 e q u a l t o 1, 1, and 0 ,
r e s p e c t i v e l y (command 110 i n t h e t a b l e ) , is r e c e i v e d , t h e CPME
becomes locked o u t t o a l l subsequent A u x i l i a r y D i s c r e t e and A u x i l i a r y
All-Call i n t e r r o g a t i o n s , but not t o Standard A l l - C a l l s (lockout
s t a t e 011).
Added r e q u i r e ment
Add new Table 3.5.2-2
(and renumber e x i s t i n g Table) a s a t t a c h e d .
T A B L E 3.5.2-2
DABS LOCKOUT STATE TRANSITION DIAGRAM
AUX. 1)lscrc-tc.
Lockout
State Prior
AUX. Dlscrete
To Interrogation
STD. All-Call
000
001
01 0
,.ockouc s t a t e i l l
e f r c r l ;,flcr i 1 1 1 erl-a>[:at irbn
011
1.00
101
110
DL5, Blt 5 of Interrogation
-DL4,
Bit 4 of Interrogation
IT, Bit 3 of Interrogation
110
.
1 1I
OXX
101
111
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Para. No.
Reason for Change
11
3.5.6.1
Change continued
Change
3.5.6.1.3 Notes on CPME-to-Sensor Radio Link Calculations.To determine the signal levels produced at a sensor RF port
by a CPME, the following equations are used:
P + G1 - L + G2 = Pi, where
0
Po is the power output from the CPME RF port
G1 is the gain of the CPME antenna system
L is the free space loss
G2 is the gain of the sensor's antenna system
P is the resulting power at the sensor's RF port.
i
3.5.6.1.3.1 CPME Antenna System Gain.- The CPME uses a 14 dB
gain horn antenna (see 3.7.2) and has a loss of 6 dB in the cable
which connects the antenna to the CPME RF port (see 3.7.3), which
results in G1 = +8 dB.
3.5.6.1.3.2
L
=
97
Free Space Loss.-
+
20 log (Range x Freq), where
L is the free space (no atmospheric attenuation) loss in dB.
Range is the distance from the CPME to the sensor in statute
miles.
Freq is the operating frequency in GHz. The CPME uses a
frequency of approx. 1 GHz (see 3.5.6.3).
3.5.6.1.3.3 Sensor Antenna System.- For purposes of calculation,
a sensor with a +28 dB gain antenna, 5 dB elevation loss due to
antenna beam shaping, and 2 dB cable loss has been assumed, giving
G2 = +21 dB.
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Page
P a r a . No.
Reason f o r Change
12
3.5.7.2.2
No ELM; reworded
for clarity
Change
D e l e t e e n t i r e paragraph and s u b s t i t u t e :
3.5.7.2.2
Extended C a p a b i l i t y Code.I n response t o a c o r r e c t l y
a d d r e s s e d i n t e r r o g a t i o n w i t h RL=1 and MSRC=0001, t h e CPME s h a l l
t r a n s m i t a Corn-B r e p l y w i t h a n MSRC code of 0001 i n t h e l e a d i n g
f o u r b i t p o s i t i o n s of t h e MB f i e l d and a z e r o i n t h e f i r s t b i t
p o s i t i o n of t h e extended c a p a b i l i t y f i e l d ( b i t p o s i t i o n 37 of t h e
Comm-B d a t a f i e l d ) t o i n d i c a t e l a c k of ELM c a p a b i l i t y .
12
3.5.7.2.3
3.5.7.2.4
To make room
f o r added
paragraphs
Renumber a s p a r a g r a p h s 3.5.7.2.4
12
3.5.7.2.3
Added r e q u i r e ment f o r s t a t u s
indication
Add new paragraph a s f o l l o w s :
and 3.5.7.2.5.
3.5.7.2.3
CPME S t a t u s . I n response t o a c o r r e c t l y addressed
i n t e r r o g a t i o n w i t h RL=1 and MSRC=0001, t h e CPME s h a l l t r a n s m i t
a Comm-B r e p l y w i t h b i t s 38 through 46 d e f i n e d a s f o l l o w s :
B i t 38:
B i t 39:
Bit
Bit
Bit
Bit
Bit
Bit
Bit
40:
41:
42:
43:
44:
45:
46:
o s c i l l a t o r o u t of phase-lock.
power f a i l (two minute t i m e r which i s a c t i v a t e d
a t power-up)
i n s i d e of encl.osure under-temperature.
i n s i d e of e n c l o s u r e over-temperature.
miscellaneous f a u l t conditions.
ATCRBS l o c k o u t s t a t e .
ATCRBSIDABS A l l - C a l l l o c k o u t s t a t e .
a u x i l i a r y (DABS-only) A l l - C a l l l o c k o u t s t a t e .
a u x i l i a r y d i s c r e t e address interrogation
lockout s t a t e .
.
(Note: t h e l o c k o u t s t a t e s r e p o r t e d by s t a t u s b i t s 43-46 a r e
t h e l o c k o u t s t a t e s i n e f f e c t a f t e r t h e Comm-B r e p l y h a s been
completed). The f o u r s t a t u s b i t s i n d i c a t i n g t h e s t a t e of t h e
lockout l a t c h e s s h a l l a l l be s e t e i t h e r t o zeros o r t o r e f l e c t
t h e p r o p e r l o c k o u t s t a t e ( 1 = locked o u t , 0 = n o t locked o u t )
under c o n t r o l of a s w i t c h ( l o c k o u t s t a t u s s w i t c h ) . The f i v e
" f a u l t b i t s " (38-42 above) s h a l l b e OR'ed t o g e t h e r and t h i s b i t
s h a l l b e t r a n s m i t t e d a s t h e FR b i t ( b i t 1 9 of s u r v e i l l a n c e o r
Comm-B r e p l y ) . T h i s FR b i t , and a l l t h e o t h e r s t a t u s b i t s , s h a l l
be t r a n s m i t t e d e i t h e r a s a l l z e r o s o r a s t h e CPME s t a t u s d i c t a t e s
under c o n t r o l of a s w i t c h ( I n h i b i t S t a t u s Switch).
Page
Para. No.
Reason for Change
13
3.5.7.2.5
Add explanatory
information
Change
Delete old paragraph 3.5.7.2.5 and substitute new paragraph
renumbered 3.5.7.2.6.
3.5.7.2.6 Alert and Flight Rule Bits.- Bit No. 6 (Alert)
in downlink Surveillance and Corn-B transmission shall always
be transmitted as a zero by the CPME. Bit No. 19 (Flight rule)
in downlink surveillance and Corn-B transmissions shall be
transmitted as defined in paragraph 3.5.7.2.3 (CPME status).
13
3.6
No ELM
In second line delete "and ELM".
14
3.6.2
No E M
Delete entire paragraph.
14
3.6.3
-
Remember as 3.6.2.
14
3.7.1.l(c)
No Mode 2
Delete sub-paragraph.
Renumber as (c), (d) and (e).
15
3.7.1.1 (g)
Consistency
with two output
levels
Delete and substitute (f): "Controls for varying the transmitter
output power (see 3.5.6.1) "
.
Renumber as (g), (h) and (i).
15
3.7.1.l(k)
No switch is
required
Renumber as (j) and change to read:
(see 3.7.4) ."
"Transmitter source,
15
3.7.2
To reflect items
actually required
In second line change 1+0.5 dB" to "+1.0 dB". Add at end of
paragraph: "A low-loss mylar radomeand suitable mounting
hardware for the horn shall also be provided."
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